↑ Michael John Bradley (2006). The Birth of Mathematics: Ancient Times to 1300. Publisher Infobase Publishing. ISBN 0816054231. Trang 70, 85.
↑ Krishnaswami Alladi, John R. Klauder, Calyampudi R. Rao. The Legacy of Alladi Ramakrishnan in the Mathematical Sciences, Springer Mathematics and Statistics Collection, SpringerLink: Bücher. ISBN 1441962638. Trang 193-194.
